Add RR3 Asset Extraction & Management System

Cross-Platform Scripts:
- extract_z_asset.sh: Linux/Unix single file extraction
- batch_extract_z_assets.sh: Linux/Unix batch extraction
- pack_z_asset.sh: Linux/Unix asset packing
- extract_z_asset.ps1: Windows PowerShell extraction

Server Integration:
- AssetExtractionService.cs: C# service for ZLIB extraction/packing
- AssetManagementController.cs: API endpoints for asset management
  - POST /api/AssetManagement/extract
  - POST /api/AssetManagement/pack
  - POST /api/AssetManagement/batch-extract
  - GET /api/AssetManagement/list
- Registered AssetExtractionService in Program.cs

Features:
- Extracts .z files (ZLIB compressed textures/data)
- Packs files to .z format with ZLIB compression
- Batch processing support
- Cross-platform (Windows/Linux/macOS)
- Server-side API for remote asset management
- Path traversal protection

Documentation:
- ASSET_EXTRACTION_GUIDE.md: Complete integration guide
- Tools/README.md: CLI tool documentation

Based on: Tankonline/Real-Racing-3-Texture-Extraction-Tool
Converted to cross-platform bash/PowerShell scripts + C# service

Ready for .pak asset extraction when files arrive from community

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

RR3CommunityServer/obj/Release/net8.0/RR3CommunityServer.GlobalUsings.g.cs

@@ -0,0 +1,17 @@
+// <auto-generated/>
+global using Microsoft.AspNetCore.Builder;
+global using Microsoft.AspNetCore.Hosting;
+global using Microsoft.AspNetCore.Http;
+global using Microsoft.AspNetCore.Routing;
+global using Microsoft.Extensions.Configuration;
+global using Microsoft.Extensions.DependencyInjection;
+global using Microsoft.Extensions.Hosting;
+global using Microsoft.Extensions.Logging;
+global using System;
+global using System.Collections.Generic;
+global using System.IO;
+global using System.Linq;
+global using System.Net.Http;
+global using System.Net.Http.Json;
+global using System.Threading;
+global using System.Threading.Tasks;